ToggleEnhancedA11yModeItem

Announce more than the minimum to a screen reader.

SEMANTICS-ASSUMED: the name specifies no behaviour, so this settles on the one an editor can honour — how much the selection announcer says. Off, it names the selection; on, it also reads back position and size, which a keyboard user otherwise cannot get at. Read it with editor.user.getIsEnhancedA11yMode(); useSelectedShapesAnnouncer is what consumes it today.

useEnhancedA11yMode is deliberately NOT exported alongside it. An earlier version of this file had one backed by a module-level boolean — so each caller got its own copy of the state, and nothing read any of them. The preference is the single source of truth, and tldraw's reference documents only the menu item.